1. Technical Field
The present disclosure relates to a radar device that detects a reflected wave signal that is reflected by a target.
2. Description of the Related Art
Radar devices have a configuration that includes an analog circuit unit that converts a high-frequency reflected wave signal received in a reception antenna into a baseband signal, and a digital circuit unit that carries out prescribed signal processing on the baseband signal. The gain of the analog circuit unit (for example, a variable gain amplifier (VGA)) fluctuates due to fluctuations in the temperature around the radar device.
Therefore, in a case where the gain deviates from a predefined assumed value, it becomes difficult for a radar device to detect desired reception signals, and detection accuracy for reflected wave signals in the radar device deteriorates. Radar devices are thus required to suppress gain fluctuations even when temperature fluctuations occur.
In “Resolution Below the Least Significant Bit in Digital Systems with Dither”, John Vanderkooy and Stanley P. Lipshitz, J. Audio Eng Soc., Vol. 32, No. 3, 1984 March, it is disclosed that, by applying a thermal noise signal of a prescribed level, a signal in an analog-digital converter (ADC) is quantized with high resolution by dithering.
In Japanese Unexamined Patent Application Publication No. 2005-77137, it is disclosed that in order to increase the resolution of signal quantization in an ADC by dithering, a noise generator that generates a prescribed dither signal (white noise) and a digital low-pass filter that removes high-frequency components (noise components) caused by the addition of the dither signal from quantization data output from the ADC are provided, and quantization errors in sampling are reduced and the resolution of signal quantization of the ADC is improved even when the bit length of the ADC is short.